feat: ESP32 DIY platform Phase 1 — marketplace with mock payment & flash token flow

- React+Vite frontend (dark theme, role-based routing: admin/seller/buyer)
- Express+Prisma+PostgreSQL backend with JWT auth and audit logging
- MinIO object storage with backend proxy for CORS-free firmware delivery
- Mock payment flow (order → mock-pay → FlashToken) for pre-business testing
- FlashToken lifecycle: issue → validate → esp-web-tools manifest → consume
- Admin approval workflow for project/product submissions
- Toss Payments integration guide (TOSS_PAYMENT_GUIDE.md) for live keys

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

frontend/nginx.conf

@@ -0,0 +1,36 @@
+server {
+    listen 80;
+    server_name _;
+
+    root /usr/share/nginx/html;
+    index index.html;
+
+    client_max_body_size 512M;
+
+    # React SPA — 모든 경로를 index.html로 fallback
+    location / {
+        try_files $uri $uri/ /index.html;
+    }
+
+    # 백엔드 API 프록시
+    location /api/ {
+        proxy_pass         http://platform-backend:3201/api/;
+        proxy_set_header   Host              $host;
+        proxy_set_header   X-Real-IP         $remote_addr;
+        proxy_set_header   X-Forwarded-For   $proxy_add_x_forwarded_for;
+        proxy_set_header   X-Forwarded-Proto $scheme;
+        proxy_read_timeout 300s;
+        proxy_send_timeout 300s;
+    }
+
+    # 정적 에셋 캐시
+    location ~* \.(js|css|png|jpg|jpeg|gif|ico|svg|webp|woff2?)$ {
+        expires 1y;
+        add_header Cache-Control "public, immutable";
+    }
+
+    # gzip 압축
+    gzip on;
+    gzip_types text/plain text/css application/json application/javascript text/xml application/xml;
+    gzip_min_length 1000;
+}